Answer:
The term "ethical relativism" encompasses a number of different beliefs, but they all agree that there are no universal, permanent criteria to determine what may or may not be an ethical act. God granted no divine command, and human nature displays no common law. Consequences have no bearing because each person or society may interpret the “rightness” of each consequence differently.

Ethical relativism teaches that a society’s ethics evolve over time and change to fit circumstances. Ethics refers to a corporate determination of what is right or appropriate versus what is wrong or inappropriate. This is as opposed to morals, which refers to an individual's determination of right and wrong. Morality and ethics do not always align; someone may consider it morally wrong to eat meat but also believe it is unethical for a government to force others to be vegetarian. Or a parent may agree with the state's law that prohibits underage drinking but may allow his own child to take a sip of champagne at a family function.

There are several facets of ethical relativism, which states that universal truth is either a myth or impossible to determine, but at the same time admits that ethical behavior does exist. The various views within ethical relativism stem from different opinions on whether ethics are based on culture, careful analysis of the world, or personal opinion.

CULTURAL RELATIVISM
Cultural relativism is often held by anthropologists who want to analyze a culture without bringing in their own biases. Cultural relativism says that "right" and "wrong" should only be considered within the context of the culture and environmental influences of a society. If a society says something is good, then it is good for them. Cultural relativism does not judge any given system of ethics.

Cultural relativism leads some anthropologists to decry missionary activity among indigenous peoples. The thinking is that a culture should be left undisturbed and that evangelizing a lost tribe is tantamount to destroying the culture. Some will even defend practices such as cannibalism and headhunting in the name of cultural relativism—who are we to say that another culture is wrong? We don’t eat people, and they do; it’s all relative.

The Bible allows for differences in culture. In Acts 15:19-20, James exhorted the Jewish believers in the church to stop loading unnecessary burdens on the new Gentile converts. The Gentiles did not have to give up their cultural identity and become “Jewish.” In Christ, they were all one. “For there is no difference between Jew and Gentile - the same Lord is Lord of all and richly blesses all who call on him” (Romans 10:12). At the same time, the Bible presents a standard of righteousness that extends to all cultures, everywhere. Murder is always wrong, even if a particular culture says it isn’t. So, there may be aspects of a culture which can be embraced and even celebrated by a believer in Christ, and there are other aspects which need to be abandoned (if the Bible calls them sinful). Culture does not dictate truth; God does.

PRAGMATIC ETHICS
Pragmatism is the belief that the “rightness” of an action is determined by the practical consequences of that action. Pragmatism asks the question “Does it work?” Pragmatic ethics says that, if something “works” for society, then it is good. And ethics need to change as new discoveries are made and logical theories are put into practice. Prohibition is a classic example. American society went from accepting alcohol to making it illegal to accepting it again. Banning alcohol was found to be impractical, so the ethics of the nation changed. Currently, laws such as legalizing marijuana and gay marriage are passing in states which not so long ago would never have considered such things. At the same time, medical discoveries have put more and more pressure on the tobacco industry. Changes in law reflect changes in perception of what will be best for the society at large as well as what is practical.

Self-adjustment of a society's ethics is normal—clothing styles, which reflect ethics, have changed many, many times in the last hundred years. And it's good for a culture to correct its ethics, as the West has done with slavery. The Bible records how the ethics of Jewish Christians changed when Peter discovered that the church is free from Jewish kosher laws (Acts 10:9-15).

But ethics without a firm foundation are useless for anything other than reflecting the beliefs of a particular people group at a certain time. God calls us to know the truth (John 8:32) and worship Him in truth (John 4:24). It is foolish to base choices of right and wrong only on pragmatism. The easiest way to do something may be efficient and therefore pragmatic, but the easiest way may not be the best way. Also, trying to determine morality based on consequences is unwise. For one thing, we cannot foresee all the results of an action; we can only guess. Only God knows the end from the beginning (Isaiah 46:10). For another thing, some good actions may have a bad result, and vice versa. What of the bank robber who is never caught? Is his crime “right” because he experienced the “good result” of becoming rich? Or what of the fireman who dies rescuing a child? Is his sacrifice “wrong” because it had the “impractical” result of his death? Consequences do not define truth; Scripture does.

MORAL RELATIVISM
Moral relativism basically says that the morality of an act depends entirely on the opinion of the acting agent. So, each individual has the right to determine morality for himself. Of course, with seven billion opinions as to what is "moral," morality quickly loses its significance altogether.

Proverbs 16:25 says, "There is a way which seems right to a man, but its end is the way of death." Moral relativism—the way that seems right to a man—leads to death. The period of the judges in the Old Testament was one of the most chaotic, tumultuous times in the history of Israel. The reason for the chaos is stated explicitly: “In those days Israel had no king; everyone did as he saw fit” (Judges 17:6; 21:25). In other words, it was a time of rampant moral relativism. With no established authority, each individual became a law unto himself. The sad results are documented in Judges, especially chapters 17-21. Individuals do not decide truth; God does.

But believers are still called to make judgment calls, and for that we need wisdom (Proverbs 3:13). Hebrews 5:12-14 says that spiritual maturity leads us to "discern good and evil." This does not mean that we judge morality by our own opinion. It means we judge it based on God's Word that lives in us (Hebrews 4:12).

Grounding ethics in God's Word will ensure their relevance beyond the lifespan of the host culture. Ethics should be more than an indicator of a society's present personality. They should reflect God's eternal wisdom in guiding how we can live together and honor Him. Ethics based on human wisdom are foolish, fickle, and fleeting (Proverbs 14:12). When humanity fell, the standards by which we live also fell. We "exchanged the truth of God for a lie" (Romans 1:25). But God's Word doesn't change (1 Peter 1:24-25).